


Flames to the Edge

by Nightlydemon



Series: Alice in Underfell [2]
Category: Underfell - Fandom, Undertale (Video Game)
Genre: F/M
Language: English
Status: In-Progress
Published: 2019-05-12
Updated: 2019-08-18
Packaged: 2020-03-01 11:00:56
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 5
Words: 8,547
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18799021
Author URL: https://archiveofourown.org/users/Nightlydemon/pseuds/Nightlydemon
Summary: Sans wakes up to a surprise after he lost control of his heat the night before. You wake up and realize you've gotten yourself into a cohabitation situation.Future warnings to come, if applicable.





	1. Chapter 1

Sans groaned as he rolled off his mattress. He reached for the spot he always left his heat suppressants on half-asleep autopilot. He cracked the bottle open with a small pop and shook out two pills. A rustle came from his bed and his eye sockets snapped wide open. He stared at the wall for a long moment before swallowing his medication and washing it down with mustard and grabbed a less dirty sock. He turned to crawl back under his blanket and rub one out before starting his day. He paused as he noticed a sleeping body wiggling under the blanket. The little skeleton turned away and counted to ten before looking back. Yep, there was a sleeping body in his bed. What the fuck happened last night!?

Sans closed his eyes and tried to remember everything that happened the day before. He woke up, took his pills, took care of his excess heat magic, went to work, fell asleep, and then... what? He sat down on his mattress and rubbed his skull trying to get to the memories. There was a sound and he hadn't taken his second dose like he was supposed to. Then there was those few minutes when Papyrus pulled him out of the fog. What else was there? He sucked a deep breath through his nose holes and the key detail hit him. He smelled _her_. He still could and his mind tingled with the heat magic still flowing through him. The body in his bed was an eligible mate and without his suppressants, he lost control.

 _Shit. Shit! SHIT!_ Sans thought before he reached into his rib cage and grabbed the core of his soul.

"Fuck," the little skeleton whispered. Right in the middle of the fluttering crimson heart was a spot of purple. It didn't seem to have burrowed that deep yet, he could still pull it out with minimal damage. He just needed to be very careful since he only had 1 HP.

Sans was just about to carefully reach in and pull when a gentle whimper came from the sleepy bundle. On pure instinct he shoved the precious piece of himself safely back into his rib cage. He twisted around to look at the person now hogging his blanket. The deep red locks poking out from under the thick fabric looked so soft and his residual heat magic started to make his head spin. He tried to shake the magic out of his skull. He wasn't going to lose it now. The form rolled over slightly and the blanket moved down to reveal a human face. She was so beautiful, so soft, so warm. He closed his eyes and grabbed his wrist to keep from touching her. He needed to keep control, he wasn't going to let his heat win out. Stay. In. Control.

Sans stole one more peak and those mesmerizing green eyes caught in his sockets. The heat exploded in his chest. It was over. The heat magic that built over the night won.

 

You woke to see the horny little skeleton from the night before shivering while gripping his wrist. The details after the tall skeleton were a tiny bit fuzzy, but you could still remember most of it. The rocky cavern and the flowers were pretty vivid, though you weren't sure where your clothes had disappeared to. Then there was a mind numbing arousal, almost like it took control, then there was the sex that gave you your first multiple orgasm. You weren't sure if it was the flowers or that magic dick, but you were curious about testing it out. For scientific purposes, of course. Sans, as your recalled the taller skeleton calling him, opened his eyes and for a split second you thought you saw something more than the eyes of a hunter.

"Mornin', Sweetheart." The words rumbled out in that husky baritone voice. His hand traced your face. They were hot, but it didn't freak you out this time. You sat up and stretched your neck and shoulders. It was almost instant how quickly Sans had his arms around your waist.

"Hah!" you gasped as he placed little kisses and nips across your collar bone. Your hand found it's way to the back of his skull as he started to work you over. Your body started to tingle under his wandering hands. You guessed you'd get to test your theories sooner than expected. Your breath hitched as he clamped down on your breast. You felt his femur start rubbing against your folds and your head lolled back. You felt his tongue slide under your chin and his femur coated in your slick.

"Ah, yer as tasty as ever, Sweetheart," Sans chuckled. His tongue dove into your mouth and you ground your hips into his knee desperate for more friction. You wrapped your leg around his hip as he pulled away. "I wanna savor you."

You twisted your body to pin the little skeleton to the grimy mattress. He let out a small grunt before that sly, sharp-toothed grin spread across his face. You pressed your lips to his teeth before you let your tongue travel to his cervical vertebrae. Your hands found their way up his shirt to caress his ribs. Your curiosity compelled you to see if you could touch the space between them.

"Gha! F-fuck, Sweetheart. You waste no time," Sans huffed as your fingertips grazed the inner part of his ribs. You made a mental note of how sensitive they seemed to be. For science. Your other hand pushed his shirt up and your tongue trailed down his sternum. You lapped at his hot bones, laying gentle little nips when you could. His little gasps and subtle moans drove you further. Your pussy twitched when you felt the ribs on his large dick press into your lower breasts. You let your finger tips brush against his hip bones as you pulled his shorts down. Within seconds, that bright red magic cock bounced out in front of your face. You could swear it's glow was pulsing with desire. You grew curious about how it would taste.

"Hah, Doll. Hehehe, s-so eager," Sans whispered. His voice dripped with lust as you took the head into your mouth. You could faintly taste cherries. It was more like the delicious fruit instead of the nasty artificial flavor found in candy. You slurped and rolled your tongue around the tip and you let one hand slide up the shaft. Your fingers plipped over each and every ridge. You stopped when you felt a bony hand rest in your hair. A small growl escaped your throat as you carefully peeled it away with your free hand. You slurped and stroked up and down on his delicious dick until your arousal was too much to bear, his flavor growing more intense as his pre dribbled over your tongue.

You crawled up the little skeleton's body and allowed your tits to brush teasingly over his twitching length. Sans allowed his hands to rest on your hips as soon as they were within range. A mischievous grin spread across your face and you gripped his wrists to pin his arms next to his head. He let a drop of drool slide from his jaw as he watched you slowly position yourself over his throbbing cock. You slide your throbbing clit over the ridges on it's spine. A needy whimper squeezed out of your throat as the tingling sensation had you just at the edge. You guided yourself down and the tingling feeling screamed through your body. You let yourself adjust to his mass filling you before you started to thrust yourself on it. You cried out your delight as each and every ridge pushed you closer to your already looming release.

"F-fuck!" you cried out. Little stars bloomed into view as your core gripped around Sans' beautifully textured rod. You couldn't remember when you let go of his hands and it didn't take long for them to be on your hips. He thrust up hard the instant your body relaxed. You pressed your hands to his ribs for balance as he bucked into your tender G-spot.

Sans let his head loll back as he kept bucking like a bronco. You revealed in the delicious sounds you both were making. A particularly rough buck tipped you over the edge again. All you could see was white when his thick cock twitched deep within your walls. An explosion of heat filled your over worked hips and splattered over your thighs. You didn't know how long your orgasm lasted, but when your senses started to come back, the little skeleton was looking up at you with a slightly surprised look on his face. You rolled off the monster and curled your arms around his chest to bask in the afterglow. He ran his hand through your hair before placing a gentle kiss to your head.

"How was it, Sweetheart?" Sans cooed. You pressed your lips to his teeth and rubbed your hand along his cheek bone. All your questions about what was so amazing from the night before were answered: it was that magic dick.

"That's was amazing," you heaved out. He let out a deep chuckle and opened his mouth to say something, but wasn't able to get it out.

"Sans! Get out of bed and come eat breakfast, you worthless pile of bone!" a very loud, grating voice called from somewhere else in the house. You recognized it as the larger skeleton monster from yesterday.

"Shit. I gotta go, Sweetheart," Sans commented before crawling off the filthy, and now soaked, mattress.

"Sans! Do not make me come up there!"

"I'm coming!"

The little skeleton dug through a basket of clothes for a short while before he produced a wrinkled shirt with a Jolly Roger on the front. He sniffed it before handing it to you.

"Here. I'll, uh, get your clothes while I'm on break. See ya later, Sweetheart." You nodded and pulled the shirt on. It was bigger than you thought it would be and covered most of your body, but definitely didn't feel like wearing a sack dress.

You stretched out a bit and started looking around the room more. It was like walking into a freshman boy's dorm room. It was simultaneously spartan and a total mess, piles of dirty clothes that sort of smelled like they hadn't been washed in months. There was a lamp on an old dresser that most certainly had seen better days with a broken flashlight stuffed into the socket. The most shocking thing was a spinning whirlwind of garbage just floating in the corner. It was odd enough that you almost missed the pile of dirty socks in the other corner. Your skin crawled at the realization you actually slept in such a filthy room.

The door flew open. Your blood ran cold as the tall skeleton from yesterday stood in the doorway. You tried to get to the window when the new monster stepped towards you, but you only made it two steps before his hand gripped your upper arm. You were dragged kicking at the air out of the room, down a set of stairs, and roughly sat at a small table. Sans was in the chair opposite looking a little defeated. Your mind raced with panic until a plate of fruit covered waffles was placed in front of you.

"Here. My worthless brother seems to forget that breakfast is the most important meal of the day. You are lucky, Human. I, the Great and Terrible Papyrus, am a very astute master chef! I must have a talk with him about the appropriate manner in which to treat Datemates," the large skeleton shouted. You tentatively ate the food in front of you. It was delicious, but the overall mood of the entire breakfast was very tense, and a little embarrassing. It was a very quiet meal. When the food was gone and the kitchen cleaned, the taller skeleton started to drag the smaller to the front door.

"You should stay here for now, Human. Sans and I must attend to our duties. Feel free to help yourself to any food in the fridge," Papyrus announced. You waved them off, mostly out of habit with the shock still relatively fresh in your mind. That was not what you expected after getting caught with your pants literally gone.


	2. Chapter 2

"Dismissed!" Papyrus announced to the dog guards with Sans still tucked under his arm. The guards left to perform the duties they were just assigned. As soon as the skeleton brothers were alone, the smaller was harshly tossed into a snow bank. He sat up a shook the snow off his hood.

"What the hell, Boss!? What'd I do this time!?" Sans snapped. He quickly started to cower when the shadow of his younger brother engulfed him. Papyrus glared down at the small skeleton.

"End this mess you have gotten yourself in. The entire situation your new marriage has put us both in is unacceptably tedious and unpredictable," Papyrus commanded. His words echoed off the trees. Sans scoffed and started to stare at his shoes. He was having a hard time finding something to deny that statement. All he could do was kick at some snow and mumble something under his breath.

"What was that? Speak up, Brother!"

"I said hand us both to the king, then! I'm not gonna fuck with the inner workin's o' my soul!" Sans snapped. He squared his shoulders and held his head high. The little skeleton returned his younger brother's stony glare. Papayrus blinked with slight surprise. He wasn't used to the little skeleton showing determination to him.

"Sans-," the taller skeleton started.

"When do ya think the next time I'm gonna find anyone so much as willin' ta touch me?!" The little skeleton threw his arms wide. "This may be my only chance to have any form o' relationship!" Papyrus snatched the little monster up by his collar.

"You are making a mistake that will get you executed! Stop thinking with your dick and hand the human to the king before it is too late!" he shouted mere inches from his brother's face.

"It's my mistake ta make!" Sans snapped. He was dropped to the snow and let out a pained grunt. Papyrus stepped over him and started towards his puzzles.

"Very well. You will be responsible for showing her how things work here, as well as keeping her happy. Now get to your post and try not slack off. I will have a discussion with the other guards later to cover for your miserable lack of discretion," the taller skeleton announced. Sans watched his younger brother disappear into the snow covered forest. He brushed more snow off and shortcut to his post before laying his head down for a quick nap.

 

You wiped the sweat off your forehead and looked at the half cleaned room with a bit of pride. You had managed to get most of the stains out of the carpet, stop the garbage tornado, and wash all the laundry. You still needed to steam clean the mattress, put the sheets you found in the laundry pile on it, and wipe down the walls, but the level of progress you'd already made had you feeling accomplished for the day. The dryer buzzed from the first floor and you went to retrieve the last load of socks. After a good half hour, you came to the conclusion that none of them had mates. You were also pretty sure they were all left socks for some reason. Your stomach screamed it's empty state at you while you were trying to remember if the bright green and purple striped sock was that color before going through the wash.

You pulled a hand-sized Tupperware container from the back of the fridge and cracked it open to see what it was. It looked to be a variation of vegetarian lasagna and it smelled pretty okay to eat. You found a fork took a bite. Other than being cold, it was delicious. You tore into the rest of the dish until it was gone. After another bout of digging through the storage area next to the laundry room, you found a tall enough step ladder to allow you access to the kitchen sink. Papyrus's ability to wash the dishes with a sink that tall would have baffled you more if he wasn't so insanely tall. You heard the familiar plip of Sans doing his teleport thing as you finished rinsing the soap off the fork.

"Well, this is a very nice view. Absolutely _booty-ful_ , Sweetheart," Sans teased. You looked down to see the little skeleton looking right up the shirt he let you borrow. He was holding your clothes from yesterday. They smelled a little like a fish pond and you knew you'd have to wash them before putting them back on. Considering clean clothes, you also realized you hadn't showered since you fell down that hole. You were in desperate need of one.

"Glad you like it, but this _booty_ could use a bath," you chuckled as you stepped down from the ladder. You foot had barely hit the floor when his arms wrapped around your waist. His hands wandered over your body and you felt his breath on the back of your ear.

"Then I guess I'll have ta give ya a thorough tongue bath," Sans purred. He slowly ran his tongue from the nap of your neck up to your ear. Your body melted into him as the idea tempted you to agree. You gently twisted around in the little skeleton's arms to face him and place a sweet peck to his forehead.

"As fun as that sounds, I think a proper bath is a better idea," you mentioned. Sans scooped you up and wrapped your thighs over his hips. He buried his face between your breasts and breathed in deep.

"Ya smell delicious, Sweetheart. Ya sure ya don't want me ta lick ya clean?" he pleaded. The look in his eyes had you really close to accepting, but you still hadn't found the bathroom. You shook your head.

"I'm fine with just getting a normal bath right now. You wanna join me?" you asked teasingly. Sans light up and started towards the door under the stairs. He took two steps before your weight was too much for him to hold and you both hit the floor. He started to chuckle as your bodies tangled together with you on top. When you managed to get to a sitting position, you noticed a bright yellow goo clinging to your shirt and his jacket.

"Guess I gotta join ya now," the little skeleton commented. He sat up and wrapped his arms around you and in the blink of an eye, you were in a pale blue bathroom. Sans gently set you on the floor while he set about drawing a bath. By the time you had gotten naked, he'd poured a generous amount of bubble bath into the running water and the small room instantly started to smell like lavender.

"Bubbles?" you asked completely on impulse.

"Oh, sorry. I've been making Papyrus's baths since he was little. It's become a habit," Sans stated lazily. He moved to empty the tub and you wrapped your fingers in his.

"It's fine, just caught me off guard. So, you're the older brother?" you asked tentatively.

"Yeah. Just been us for the past ten years. Kinda hard ta believe he's twenty already," Sans mused as he started pulling his clothes off. He stared off like he was mourning a lose of some kind. You pulled him into a hug and pet the back of his skull for a bit. A few moments later, you were hoisted into the air and set in the hot bath surrounded by sweet smelling bubbles. The water was shut off and the little skeleton hopped in with you.

Sans started rubbing your whole body with a poof sponge and you were certain it was an excuse to keep touching you. You just relaxed and let him wash you. It was nice. None of the guys you'd been with on the surface were willing to do this for you, not that you ever actually asked them. A small observation brought a question to your mind.

"Hey, Sans. Why aren't your hands hot right now?" you asked. He paused and you could hear him swallow before answering.

"Well, I took my heat suppressants. Monsters go through periods o' high sexual drive and medication is one o' the only ways ta control it. It makes us really hot, so we call it Heat," Sans explained. You were about to ask another question. "I forgot to take them when I was supposed to yesterday, and they only last six hours, so this morning was... instinct."

"Should I feel a bit insulted?"

"Nah, Sweetheart. I don't need ta be in heat to want ya like that," Sans reassured. His tongue dove int your mouth and you wrapped your arms around his shoulders. The rest of the bath was spent chatting, joking, and washing each other. When you were both clean, you tossed the dirty clothes in the wash. Sans went about putting on clean clothes, bid you farewell, and went back to work. You felt so much better after the bath and set back to cleaning that filthy room.


	3. Chapter 3

Sans ignored the jeers and insults thrown at him as he approached the bar at Grillby's. He took his normal seat and put his head in his hands. It didn't take long for the purple fire monster to greet him.

"Rough day at work? Didn't see you yesterday, Sans. Wanna talk about it?" Grillby stated. He started to pour a small glass of mustard.

"I need somethin' stronger, Grilbs. I really fucked up this time," Sans forced out. The fire monster put the glass of mustard in front of the little skeleton.

"You know alcohol counteracts the heat suppressants. I'm not giving you booze. If you're struggling, I can help you in some other way," Grillby said. Sans grabbed the fiery hand and shortcut into his friend's upstairs apartment. The purple monster shook the dizzy from his head. "Hand-job it is, but you will have to suck me while I do it."

"Bitch, I summoned a pussy for ya durin' yer heat! Ya have any idea how hard that was to maintain with yer dick constantly movin'?!" Sans snapped.

"That's because you are far more submissive than me. I'm willing to jerk you off, take it or leave it. No one else is going to." Grillby shrugged. He shook his head slightly with indifference.

"That's not why I shortcut us here. I fucked up."

"How?"

Sans carefully reached into his rib cage and pulled out the core of his being. Grillby took a closer look before stepping back a little.

"When did you get married?" Grillby commented more out of shock than curiosity.

"Last night. I forgot my pills and lost control. I didn't think she'd even have a compatible soul," Sans explained as he quickly stuffed his core safely back under his ribs. "Paps told me ta get rid o' her and I basically told him ta fuck off."

"Obviously you weren't thinking at all. Guess you just have to get used to the idea of maintaining a relationship. Who's the monster? Purple souls aren't very common," Grillby commented.

"Well, ya see. She's sorta," Sans paused and glanced between the floor at the purple fire monster. "Human." Grillby blinked as a very awkward silence grew between the two monsters. Flickering hands rubbed a fiery face.

"She's a what?" Grillby asked very slowly.

"A human. I fucked and married a human," Sans clarified.

"End this! Remove the bond and hand her to the king before you get caught and executed! Don't be stupid!" Grillby snapped.

"Oh for Error's sake! When do ya think I'm gonna find another mate!?"

"I don't care if you ever find a life long mate! That human is going to get you dusted if you don't hand her over!"

"But she's hot!" Grillby gagged a little before he paced back and forth for a bit. He scratched behind his neck in thought. He sighed before turning back to Sans.

"Look, your Heat must be effecting you deeper than you realize. When it's over, you'll have a clearer view of the entire situation. Hopefully you'll stop being stupid then. As of right now, I need to get back to my bar. Ink only knows what's going on down there," Grillby stated. Sans nodded and shortcut both of them back down to the bar.

Grillby went about servicing his bar. A few minutes later he set a slightly burnt burger and a full bottle of mustard in front of Sans. The little skeleton ate his food and drank the mustard before announcing to put it on his tab and left. The fire monster waved him off with an expression bordering on absolute rage and intense worry.

 

You had just finished wiping down the walls and were relieved to find they aren't actually as dirty as you thought they would be. After several minutes of scrubbing you'd realized they were painted a dingy red and it wasn't all grime. The front door opened as you carried the wash bucket down the stairs. Papyrus was shaking the snow off his armor and promptly cleaning the mess off the floor. He looked over to see you holding the bucket. His expression turned to surprise.

"Human, did you clean my brother's room?" he asked in a pleasant tone. You nodded with a proud smile. The tall skeleton took the bucket from you and set it down before wrapping you in a tight hug.

"Do not ever leave, Human!" Papyrus demanded in a tone of pure elation. As soon as the hug started, it was over and the tall skeleton's eyes shined. "I shall prepare us dinner! Feel free to watch TV."

"I'd like to help in the kitchen if that's okay," you said as you started towards the kitchen.

"It is perfectly fine for you to relax and watch TV while I cook dinner."

"But-,"

"I do not require your assistance in my kitchen, Human!" Papyrus snapped with an almost territorial posture. You just nodded with your hands up in surrender and the skeleton relaxed and stalked dramatically into the kitchen. You took the bucket to the bathroom and emptied it in the tub before watching TV. There really wasn't anything interesting on, just an over dramatic robot clearly forcing dramatic tension. The food smells coming from the kitchen were far more engaging and the TV fell into background noise as you started to wonder how good the food would taste warm. It definitely smelled like it would be tasty.

A good half hour had passed before you gave in to the temptation to test the kitchen boundary. You carefully crept to the doorway and peered in. Papyrus had everything so organized he was barely looking at the small dishes of seasonings. You just watched in awe as the tall skeleton moved like a master chef to make food. You looked at what part of his face you could see and noticed he was just barely glancing at the well organized bowls. Could he recognize everything at just a glance? You took one tiny step past the door and the amazing dance stopped.

"Human! Please do not get in my way in my kitchen!" Papyrus shouted. It was more a warning than a threat, but you still jumped back. "Dinner will be ready in a few minutes. Please relax and be patient. I know my masterful cooking skills make that a difficult task, but I assure you the wait will be worth it."

You nodded and wandered to the couch and sat back down. You tried to put your attention on the TV, but between the boring and predictable nature and the exquisite smells flowing out of the kitchen, all you couldn't. All you could do was stare at the kitchen and control your drooling. You glanced at the clock on the TV and back to the kitchen several times. You knew it was only a small handful of minutes, but the wait was starting to feel like an eternity. You glanced back at the clock and debated whining like a dog when a timer went off.

"Human! Dinner is ready!" Papyrus called. You were at the table almost instantly. A few moments later a steaming plate of lasagna was set in front of you. It looked as good as it smelled and you picked up your fork. You paused before digging in.

"Where is Sans?" you asked. The taller skeleton's expression became annoyed.

"My brother does not eat here after breakfast. I have tried to get him to eat less grease to no avail. He is a most lazy monster," Papyrus explained. He took a bite from his own serving. You got the feeling he didn't want to go further. You just let it be and went to eating your dinner.

The flavors exploded in your mouth like a complex and harmonious symphony. The food being hot certainly brought more nuance to the lasagna. Each bite was better than the last as the flavor and texture danced across your tongue. Your body tingled with the excitement over how delicious every morsel was. It was by far the best veggie lasagna you had ever tasted, and the cheese was surprisingly not greasy at all. You tried to eat slowly, but the time between swallowing one bite and getting the next in your mouth was too long. Before you knew it, your plate was empty and you moved to get another serving. The tall skeleton held his head high with a smug glint in his eyes as you started eating a second piece. It was so perfectly prepared that you wanted more. After the last bite of your second helping, you were tempted. You thought about it and felt the tightness in your stomach. You decided you wouldn't be able to eat another bite without making it worse.

You went to grab the ladder to wash the dishes, but when you got back, Papyrus was already washing them. He seemed pretty quick at the task and was already half done. You decided to put the ladder back and the front door opened. Sans closed the door behind him and shook the snow off. You watched as the younger brother glared from the kitchen at the little piles of rapidly melting snow. The little skeleton wrapped you in a tight hug before breathing in your scent and spinning you around.

"Hey, Sweetheart! I'm home," Sans announced.

"Sans! Clean up this mess!" Papyrus shouted as he pointed to the now ice cold puddles. Sans looked down and gave an exaggerated yawn.

"Sorry, Bro. Way too tired from work," Sans said in a clearly fake tired voice. He pulled your waist close to him. "See ya in the mornin'." With that, you both were in his room with the same magic that brought you to the flower cave. You heard an exacerbated screech through the walls and you bit your tongue to keep from making the situation worse. The little skeleton let out a dark chuckle before pulling you down to the mattress and kissing you deeply. You both cuddled in comfortable silence until you both fell asleep.


	4. Chapter 4

**Summary for the Chapter:**

> Fair warning, this chapter is weird.

Sans stirred awake. His sockets stayed closed as he reached for his bottle of pills. He gripped the bottle and fished out another two pills before swallowing them and rubbing the sleep from his face. He looked towards the sleeping body next to him and smiled. He brushed the lock of red hair out of her face and the softness of her skin made his fingers tingle. The little skeleton gently pet her face as the Heat magic started to fill his skull. She was so warm, so soft. He leaned down on instinct and hovered over her sleeping lips. So soft.

"Sans! I need assistance!" Papyrus screamed through the wall. The sudden command pulled the monster from his spell and he shortcut into his little brother's room.

"What is it? I'm busy," Sans snapped. He was slightly more than annoyed at the interruption. He watched as his brother squirmed in his pajamas, pillow held protectively over his pelvis. The taller skeleton had a deep red blush taking over most of his face as he cleared his throat. He slowly moved the pillow away to reveal an unrelenting erection.

"It won't go away," Papyrus said. The little skeleton snorted in amusement.

"Guess yer havin' a _bone-_ er of a time," Sans joked. He let out a bit of a laugh.

"Sans, this is serious! I can't perform my royal duties with _this_! I really should have set an alarm to wake me up after yesterday's ordeals," Papyrus lamented.

"Ya haven't been takin' the suppressants every six hours even at night, have ya?" Sans asked with a cocked brow.

"Of course I have, you worthless bag of bones! I can't allow this confounded biology to control me, The Great and Terrible Papyrus!"

"Bro, ya gotta let Heat out. The suppressants don't make it go away, they _suppress_ it. Takin' the pills every six hours like that is just gonna make yer Heat last longer," Sans explained.

"You are a lowly cretin and pervert! I demand you tell me how to make this go away this instant!"

"Ain't my problem," Sans commented as he started towards the door.

"Sans!"

"Just rub one out like the first day, Paps." Papyrus paused before he responded.

"Is there any other way?"

"Go intimidate a monster inta takin' it."

"That is in violation of the Dating Rule Book! I will not stoop as low as _you_!"

"Then ya gotta jerk off. Have fun."

"That... Chafed. A lot," Papyrus commented. His sockets were laser focused on his feet. Sans sighed held his nasal bone. He plipped to the kitchen, grabbed a bottle of cooking oil, and popped back in front of his younger brother.

"Here. This'll help," he said as he held the bottle out. Papyrus took the bottle and stared at it in confusion. "Put some in yer hand and rub."

Sans started towards the door again to give his little brother some privacy. His hand had just landed on the knob before he heard Papyrus let out a frustrated grumble. Curiosity forced him to look back to see the problem.

"Oh, fer Ink's sake! Papyrus, yer grippin' too tight," Sans snapped.

"The Great and Terrible Papyrus does not grip anything too tight!"

"Yeah ya are! It's not a weapon, yer gonna get nowhere jerkin' off with a dust grip!"

"Then show me the proper technique if you are such an expert!" Papyrus stood up suddenly, his glowing skeletal cock bouncing with the momentum. Sans blinked in shock and just stood in his spot until it wore off a bit.

"Paps, don't be weird," was all the little monster could say. Papyrus stamped his foot and gave a stern face that said he was serious about his demand. Sans let out a tired breathe. "Fine. Sit down and try not ta make it weirder than it already is."

Papyrus sat down on the edge of his bed and waited. Sans climbed onto the super plush bedding and positioned himself just behind his younger brother. He took the younger monster's hand in his and moved to show him how to properly grip his cock.

"Like this," Sans commented as he carefully wrapped Papyrus's fingers around the stubborn hard-on. The taller skeleton let out an uncomfortable grumble at the entire situation. He slowly moved his brother's hand up and down as he kept him from tightening his grip. "See how the lube stops the chafe and a lighter grip keeps yer dick from slippin' away?"

"Y-yes, brother," Papyrus grumbled. Sans let go and moved back to let his brother do his own work.

"Good. Ya can speed up if ya want. I'm gonna go take a bath. I feel dirty," the little skeleton griped before he shortcut to the bathroom. He drew a bath and started scrubbing his bones as hard as he could trying to feel less gross.

 

You heard some muffled words from the other side of the wall and rolled over. You were in that point of waking up that a minute of pure quiet could have you falling back asleep. The rest of the house had other plans for you. You heard your new boyfriend yelling at his brother about gripping something too tight and your eyes popped open. You crawled out of bed and the argument continued for a moment before going quiet. You made your way carefully to Papyrus's bedroom door and quietly cracked it open. You watched in a stunned stupor as Sans went above and beyond showing his brother how to masturbate. You weren't sure how common this practice was among monsters, but you did know that humans never talked about it, if it happened at all. You snapped out of your flabbergasted state just in time to catch the little skeleton announce he was going to take a bath. You just stood there after he plipped away for a good minute watching the taller skeleton. You didn't expect him to have a cock that much bigger. It made sense, but you hadn't really thought about it. Your inner size queen was hypnotized by the display until you realized you were being creepy. You quietly closed the door and went down to the bathroom.

Sans was in the middle of scrubbing himself raw when you opened the door and stepped in. You closed the door behind you and started to pull you clothes off. You watched his skull twitch a few times and his eyes shift into what you were now going to call his horny look. Without a word, you climbed into the tub behind him and wrapped your arms around his shoulders. You pressed your lips to his teeth and he reciprocated your kiss.

"Mornin' Sweetheart," Sans purred into your cheek. His hand found it's way to the back of your head so his wet fingers could curl into your hair.

"You know, you're a very caring brother. I don't know anyone who's willing to help their little brother _relieve_ themselves like you just did," you whispered. Sans chuckled as he tangled his fingers into yours. It didn't take long for him to gently move your hand under the water.

"Does that mean you'll throw this dog a _bone_?" he chuckled as he managed to get your hand on his magic dick.

"Maybe," you teased and wrapped your hand around the pulsing magic between his legs. You slowly stroked up the shaft and caressed the head. Sans leaned back into you on the down stroke as you pleasured him. His breathe grew heavy and listening to his noises had your engine going. The more tiny moans he let out the faster you wanted to move. The faster you stroked, the more intense his sounds became.

"S-shit, Doll! Don't stop," he mewled. You pulled him into a deep kiss as you stroked his cock faster. You swallowed his little moans as he started to thrust into your hand under the water. The glowing appendage started to twitch until the kiss broke.

"F-fuck!" Sans groaned out as a cloud of bright red goo tinted the bath water. His cock pulsed as the colored cloud grew. The little skeleton heaved in his blissful release content in your arms. After a few moments of reveling in the after glow he let out a deep chuckle.

"Did you enjoy your treat?" you asked with a sly grin.

"Heh, I should grab my bro's dick more often," Sans commented, then a wave of disgust washed over his face. You both just sat in the tub for a shocked moment. "Th-that's not what I meant!"

You tried to hold back a laugh and failed. Sans tried in vain to get you to stop laughing so he could explain what you already knew he meant. He was several attempts in before he chuckled and announced he knew a trick. His head disappeared under the water and you felt a soft, wiggling tongue slide up your slit. You stopped laughing immediately and let out a surprised yelp.

"F-fuck!" you whimpered as you began to realize just how turned on you had been. Sans didn't waste any time plunging two fingers into you as his long tongue flick at your clit. His fingers curled just right as your looming release came closer to the surface. He slipped a third finger inside and your hands held onto his skull. He curled and pumped his fingers a little faster and your pussy clenched down hard on his fingers as you cried out your bliss. The little skeleton popped his head up and wiggled his brow bone at you.

"Th-that's not fair," you managed to get out between breathes. Sans chuckled and pulled you into his lap.

"All's fair in Love, Sweetheart," he commented. He nuzzled his face into your neck as his hands squeezed your ass. Your mind came back to you and a question you knew was gonna nag you if you didn't ask it popped up.

"Hey, how were you able to stay under so long?"

"I'm a skeleton, Doll. I don't need ta breathe."

That actually made sense and you both agreed it was time to get out of the tub and start the business for the day.


	5. Chapter 5

**Notes for the Chapter:**

> I sliced open my finger a couple days before starting on this and it still hurts to type, so it's a little short.

You and Sans descended the stairs and went to the kitchen. Papyrus was setting bowls of fruit yogurt on the table with his head hung in shame. You noticed an almost full bottle of cooking oil in the trash. You watched as both skeleton's locked eyes for a full second. The brothers looked away as an embarrassed blush spread across their cheek bones. You took your spot at the table and watched the skeleton brothers awkwardly take theirs. The meal was tense, but you could feel that it had nothing to do with you. In spite of the circumstances, the fruit yogurt was very delicious. You helped wash the dishes before waving the skeleton brothers off to work. The younger of the two turned to face you from the porch.

"I have given the other guards orders not to harm you, Human. It is relatively safe for you to explore the town now, though I suggest you do so with caution. The civilian monsters will not be so obedient, the rabble they are," Papyrus announced as he handed you a key with a sticky note stuck to it. The note had _Spare House Key_ scrawled on it. You nodded in understanding before he left to attend to his duties.

You decided to clean the mess in the bathroom that you and Sans had made before checking around the town. It dawned on you mid-tub scrubbing that you had no idea what the name of the town was. All you knew about it was that it was cold and covered in snow from what you could see out the windows. Most of the view from the windows was just snow covered trees. You finished your task and went to digging through your boyfriend's closet and dresser for something warm to wear while you took the opportunity to explore the town. It seemed like that crazy goat lady was crazy when she told you the rest of the underground was deadly. You eventually found an old leather jacket and a scarf and mitten set. The snow boots you found were too small, but for some reason you also found a pair of thermal leggings. They were covered in roses and skulls and barely worn. You had a very hard time believing that either brother wore them. You shook the ideas from your head and donned the cold weather clothing before heading out to see this town. It couldn't be very small since it had a sort of police force.

You stepped out the door and locked it behind you. You stuffed the key in your pocket and looked down the road. You could see a dreary light in one direction, and a thick fog in the other. You decided to start towards the light as you weren't sure if you could keep your bearings in the fog. You made note of the library being very close to the house, though the sign being misspelled definitely caught you a little off guard. You thought it was best to avoid the areas of snow that were splattered with blood. If all the close calls in the Ruins had taught you anything, it was that bloody spots meant deadly spikes would shoot up the instant you stepped on them. It was a miracle that you'd managed to dodge all of them. You decided to see what was down the little side road just passed the library, but the only thing that seemed of interest was the ice factory. You noticed a lot of monsters quickly ducking into their shabby little houses the instant they saw you, a lot of them ushering smaller versions of themselves wearing striped sweaters. Eventually you came to a little clearing next to the river. From the ground you could see that a lot of foot traffic came this way, but you couldn't go any further.

You made your way back to the T-section and continued looking around the little town. The air was more misery than quaint. As you ventured further down the road you passed a place called Grillby's and saw a pitifully decorated tree. It looked like a halfhearted Christmas tree with various gifts wrapped in old newspaper. The sound of someone being forcefully thrown through a door made you spin around. You watched two monsters of unknown origin brawling out of Grillby's into the street. They both looked like they had been drinking and you assumed the establishment was a bar of sorts. Papyrus' warning about the civilian monsters came to the front of your mind and you hastened you pace down the road. It'd be pretty bad if you got pulled into a street brawl. You passed a house with a large tree in front of it and noticed a little glowing star. It was in front of a duplex style building. One side said "Inn" and the other said "Shop." There was also a little igloo looking structure next to it. You decided to check out the store and do some window shopping.

"Welcome to the Sno- the fuck?" the bunny monster behind the counter cut herself off. You gave her a friendly smile and wave.

"Hello. I'm new in town and was just curious about stuff," you explained.

"How in Error's name did you, a human, get this far into the Underground?" she asked.

"I'm sorry?"

"Humans never make it past the Bridge of Death. I've only seen pictures of your kind," the sales bunny commented. Her face still held an expression of shock.

"That bridge with the gate that's too wide to stop anyone? I ran into Sans there and he sort of teleported me to some cave, then his house from there. I guess we're dating now?" you said. The entire set of events leading to your current situation were still a little confusing to you. The sales bunny's expression shifted from shock to exasperated understanding.

"I see. That worthless sack of bones is always thinking with his dick. My name's Violet, by the way. I run the shop here, and my sister runs the inn," the bunny commented. You blinked a couple times before offering your name in return.

"So, you know Sans well?" you asked.

"Too well. His first Heat cycle I had to beat him off of me with a stick. Literally, that's why he's missing a tooth," Violet explained. You chuckled a little before you continued the friendly little chat. The two of you just chatted about the town and what there is to do for fun for several minutes. You had to admit not having any G, which was apparently currency in the Underground, at a point in the conversation.

"Well, I'm about to start another Heat cycle and could use some help around the shop. If you do well, I can make a more permanent position for you here," Violet offered. Your eyes lit up at the prospect of having a job.

"Really? Oh my god, thank you so much! When should I come in?" you responded excitedly.

"I'm sure you've got your hands full with that horn-dog of a skeleton for another day or so. You can start Monday at seven," the sales bunny said.

"Great, I'll be here bright and early Monday! Only, what is today? The past few days have been a bit of a blur," you asked.

"It's Friday, dear. I understand the blur you're going through right now. My husband's heat cycle and my own don't match either," Violet explained. "If you want a safe way to get to the other side of Snowdin, the fast travel tunnel is right next door. I suggest you avoid being in front of Grillby's as much as possible. At least until you're more used to life here in Snowdin."

You thanked your new boss and waved her goodbye before you ducked into the igloo-like structure. There was a short set of stairs going down to a conveyor belt floor, similar to the kind you found in airports on the surface. You cautiously stepped on and it started moving towards a distant light at the other end of the long tunnel. It took you a significantly less amount of time to get to the other end of the tunnel than you could even imagine it would take you to run through town. You climbed the stairs at the other end and were surprised to find that the tunnel had taken you almost directly to the skeleton brother's house. You went inside and started digging in the fridge for lunch leftovers.

 

Sans swallowed his second dose of heat suppressants for the day and cracked open his lunch box. At some point in his post-breakfast shame he'd grabbed it for once. It'd been so long since he'd actually brought lunch from home instead of just shortcutting to Grillby's. He blinked at the sight of one of Papyrus' early cooking experiments. It was spaghetti with chopped water sausages. The little skeleton cocked an eyebrow trying to remember if it was one of the better or worse experiments. He eventually took a bite and the flavor was indescribable. He looked up and down the road before slipping into the bushes and dumping the contents on the ground and burying them in snow. He shortcut straight to his best friend's bar and announced his usual lunch order. He made a mental note to not grab anymore boxes from the fridge for lunch as he ate his food.


End file.
